Method of preparing calcium sulfate.



To all whom it may concern:

MAX WALLERSTEIN, OF NEW YORK, N. Y.

METHOD OF PREPARING CALCIUM SULFATE.

Specification of Letters Patent.

Fatented Feb. 18, 1908.

Application filed June 21:1907- Serial No. 380.160, (Specimens-l Be it known that I, MAX l/VALLERSTEIN, a citizen of the United States, residing at 105 East Ninetyfirst street, New York city, in the county of New York and State of N ew York, have invented certain new and useful Improvements in Methods of Preparing Calcium Sulfate, of which the following is a specification.

The object of this invention is to prepare precipitated calcium sulfate in a form differmg in certain physical respects from the usual or normal precipitate, and possessing advantages for certain purposes herein v after set forth.

With this object inviewthe invention comprises a method of preparing calcium sulfate and the product thereof. l

When calcium sulfate is precipitated from aqueous solutions by the usual methods, as for instance by mixing a suliicicntly concentrated solution of a calcium salt, as cal cium chlorid, with a soluble normal or acid sulfate or with sulfuric acid, the calcium sulfate separates as an extremely finely-divided precipitate which appears under the microscope in the form of minute needle-like crystals. I have discovered however that by offecting the precipitr'ttion in the presence of small proportions of a colloidal substance capable of serving as a restraining or retarding agent the precipitate separates much more slowly and dill'crsin character from thenecdlelike crystals above mentioned, apiear'ing under the microscope in the form of plates or tablet-like crystals of relatively large size. These crystals are found, to separate very readily from tho mother-liquorundcr theordinary conditions of filter-pressing, and to be easily washed and dried: they are found also lo pos" iss a high solution mic,- l he abovcchur-' actcristics rcudcring thcm particularly suitable. for certain purposcs, as for thc preparation of brcwing waters.

I: may proceed substantially as follows: To a solution of a suitable calcium salt, as calcium chlorid, which may bc of any desired strength but is preferably quite com-entratcd say too to twenty pcr ccnt., i add a suitable colloidal substancc, as gelatin, from one to live ounces of gelatin being preferably added to each thirty gallons of the solution, the proportion increasing with the concentration ofthe chlorid solution. There is then mixed with the chlorid solution in the proportion required to combine with the calcium therein, a solution of a suitable sulfate, as the normal or acid sulfate of sodium, or sulfuric acid, and the mixture is permitted to stand until pre cipitation is complete, the precipitation being 50 accelerated by heating if desired.

The sulfate solution may be of any desired strength, ten per cent. being a convenient concentration.

In some cases I prefer to add the gelatin or .65

equivalent colloidal substance both to thesolution of the calcium salt and to that of the sulfate. in either case the calcium sulfate will be found to separate in the plate-like crystals above referred to, subsiding quickly in the solution and readily separable therefrom.

Instead of gelatin 1 may employ other albumenoid substances; these materials having been found to possess like gelatin the 75.

be utilized for the treatment of water for the preparation of beverages, being mixed if desired with other salts capable of accelerating its solution ,or modifying its action. It is also found to be adapted for the reparation of culture solutions for lclaim:

1. The method of preparing calcium sulfate. in plate-like crystals which consists in reacting upon a calcium salt in solution with a soluble sulfate in tarding agent. 1

2. The method of preparing calcium sulfate in plate-like crystals which consist-sin reacting upon a calcium salt in solution with a soluble sulfate in. presence of gelatin.

in testimony whereof, I allix my signature in presence of two witnesses.

MAX WALLERSTEIN.

a Witnesses:

CLINTON P. TOWNSEND, CHARLES H. PQTTER.

presence of a colloidal reyeast an' the like. 86 

